1. Field of the Invention
The present invention relates to a press machine for carrying out at least one operation on chip-type electronic components which may be for example, inserting chip type electronic components such as chip capacitors or chip resistors into receiving holes of a holding plate, transferring chip type electronic components from a holding plate holding the chip type electronic components to another holding plate, or pressing out chip type electronic components from receiving holes of a holding plate.
2. Description, of the Background Art
A holding plate elastically holding a number of chip type electronic components is employed for simultaneously applying electrodes onto end portions of the chip type electronic components, as described in U.S. Pat. No. 4,395,184. This holding plate comprises a hard substrate; a thin flat plate portion formed at a central portion of the hard substrate and provided with a number of through holes; and a rubber-like elastic member which is embedded in a concave portion defined in the flat portion and provided with receiving holes which pass through the elastic member, in members corresponding to the through holes. This holding plate is adapted to form external electrodes on both ends of chip type electronic components in the following manner:
First, a guide plate, which is provided with a plurality of through holes in correspondence to the receiving holes of the holding plate, is arranged on the surface of the holding plate. Then chip type electronic components are inserted one by one into the through holes of the guide plate and downwardly pressed by press pins, and are thereby received in the receiving holes, so that the holding plate elastically holds the chip type electronic components to expose upper end portions thereof on its surface. The holding plate thus holding the chip type electronic components is then turned over and the downwardly exposed portions of the chip type electronic components are pressed against an electrode coating plate which is coated with electrode paste of silver or the like, so that electrodes are applied to the end portions of the chip type electronic components. After the electrodes are dried, a second holding plate is arranged under the first holding plate holding the chip type electronic components, on the other side of a frame type spacer of a prescribed thickness. Then the chip type electronic components are transferred from the first holding plate to the second one by press pins which are similar to those mentioned above, so that other end portions, provided with no electrodes, of the chip type electronic components are exposed. Thereafter electrode paste is applied to the other end portions of the chip type electronic components by an operation similar to the above, and then dried. Thus, electrodes are formed on both end portions of the chip type electronic components as disclosed in U.S. Pat. No. 4,664,943.
In order to insert the chip type electronic components from the guide plate into the holding plate or transfer the same from a holding plate to another one, a press machine having a number of press pins is employed. U.S. Pat. No. 4,395,184 discloses an example of such a press machine. This press machine comprises an upper plate which is vertically moved by a handle, and a number of press pins which are downwardly projected from the upper plate. A mechanism for positioning a guide plate, a holding plate and a discharge plate in an overlapping state is provided under the upper plate.
A holding plate is adapted to form electrodes on chip type electronic components of various sizes in a range of 1.6 mm in length, 0.8 mm in width and 0.8 mm in thickness to 5.7 mm in length, 5.0 mm in width and 2.0 mm in thickness, for example. In order to insert or transfer chip type electronic components of different sizes into or from the receiving holes of the holding plate, therefore, it is necessary to use press pins of different diameters. However, such press pins are generally integrated with the press machine, and hence it is necessary to prepare a plurality of press machines in response to the chip type electronic components of various sizes, with disadvantageous increase in cost.
Further, press pins are made of a hard metal such as hardened steel, and those of about 0.5 mm in diameter may be broken when they are used a little less than ten thousand times. While a single press machine is generally provided with about 2000 to 3000 press pins, the machine cannot be used if only one of the pins is broken. In this case, it is necessary to disassemble the entire press machine in order to exchange the broken press pin with a new one. Thus, the time to exchange the broken press pin while stopping the press machine is increased, leading to inferior productivity.